Armstrong was the main exponent of

Armstrong was the main exponent of the heuristic method, in which the learner is placed in the position of a discoverer.

The student investigates, experiments and finds facts by unaided effort, with the teacher only guiding.

The problem-solving method centres on solving posed problems and is not what Armstrong specifically championed.

The project method, tied to William Kilpatrick, organises learning around purposeful real life projects.

The discussion method relies on group exchange of ideas, which is different from heuristic self discovery.

H.E. Armstrong promoted the heuristic approach so that students learn science by acting like young researchers.